1. Field of the Invention
The present invention generally relates to a head mounting type image display system and, more particularly, to a head mounting type image display system which is mounted on the head portion of an observer and can project an image onto the corneas of the observer's eyeballs.
2. Description of the Related Art
Conventionally, an apparatus such as a wordprocessor, a personal computer, or the like, which allows to input characters, symbols, and the like at the position of an input position indication mark (normally, a cursor) using a keyboard and displays the input characters, symbols, and the like on the screen, or moves the input position indication mark (cursor) by operating a cursor mover such as a mouse, cursor keys, a return key, a joystick, a tracing ball, a light pen, or the like on the screen, and allows an input instruction or the like at the position of the moved cursor, is known.
Needless to say, products using these techniques are widely commercially available from various manufacturers such as Fujitsu, Toshiba, Hitachi, NEC, Apple, IBM, and the like, and such techniques are generally well known.
On the other hand, a head mounting type image display system which is mounted on the head portion of an observer, displays an image using an image display element such as a liquid crystal display element (LCD) or the like, and guides, as a virtual image, the displayed image to the eyeballs of the observer using various eyepiece optical systems such as a lens system, a concave mirror, and the like, is known.
The head mounting type image display system is a new type image display system which can be mounted on the head portion of the observer via mounting means without being held by, e.g., the operator's hand, and allows the observer to observe a large-scale image using a compact image display element arrangement therein.
Proposals as combinations of the wordprocessor or personal computer and the head mounting type image display system have been proposed.
To the knowledge of the present applicant, Jpn. Pat. Appln. KOKAI Publication Nos. 3-289615 (prior art 1), 4-22920 (prior art 2), 4-168489 (prior art 3), 5-41822 (prior art 4), 5-241767 (prior art 5), 5-250089 (prior art 6), 6-72186 (prior art 7), and 6-78247 (prior art 8) are available.
Of these prior arts, prior arts 2 and 3 disclose techniques as simple combinations of the wordprocessor or personal computer and the head mounting type image display system.
Prior arts 1, 5, 6, and 7 disclose techniques for detecting the displacement of the head portion of an observer, and moving a cursor or keyboard on the screen in accordance with the detection result.
Prior art 4 discloses a technique for detecting the visual line or line of sight of an observer, and moving the cursor on the screen in accordance with the detection result.
Prior art 8 discloses a technique for detecting the tilt, in the vertical direction, of the head, and scrolling the entire screen vertically in accordance with the detection result.
However, all of these prior arts pose a common problem when the cursor is moved to the end of the screen, and an input operation is performed.
In the operation of a normal (not a head mounting type) wordprocessor or personal computer, since the screen for displaying an image is independent from the head portion of the observer, when the cursor is moved to the end (e.g., an icon portion or the beginning of a sentence at the end of the screen) using, e.g., a mouse, and a click or key input operation is performed there, the observer can always observe the cursor in front of his or her face by turning his or her face in the display direction of the cursor in accordance with the movement of the cursor.
However, in the head mounting type image display system, since the image display element for displaying an image is integrated with the head portion of the observer, even when the observer turns his or her faces to follow the cursor, the entire image moves to follow the movement of the face. As a result, the cursor falls outside the field of view of the observer.
For this reason, since the observer cannot observe the cursor in front of his or her face by turning his or her face, he or she must follow the cursor by moving only his or her eyeballs in the vertical and horizontal directions while fixing his or her face in position.
Therefore, in the conventional system, since the observer performs an input operation while repetitively moving his or her eyeballs in the vertical and horizontal directions, or performs an operation while turning his or her eyes greatly in one direction, eye fatigue is considerable, and the observer cannot use such a system for a long period of time.